1. Field of the Invention
The present invention is directed to a housing for an implantable stimulator, such as an implantable pacemaker, with at least one electrode connector for electrically and mechanically connecting the internal components of the stimulator to an electrode lead.
2. Description of the Prior Art
Implantable stimulators, such as a pacemaker, have a housing (also known as a "can") which contains electronic circuitry and a power source (battery). The stimulator delivers stimulation energy, usually in the form of pulses, in vivo to tissue, such as cardiac tissue, via electrodes which are implanted so as to be in contact with the tissue. One or more electrode leads connect the stimulator to these electrodes. The leads must be mechanically and electrically connected to the housing. A single lead having multiple conductors, leading to respectively different electrodes, can be employed, or multiple leads can be used.
The internal components contained in the housing must be protected against the surrounding environment, especially body fluids, over a relatively long period of time. This requirement imposes high demands on all possible entry paths into the interior of the housing, and particularly on the connections of the leads to the housing. A fluid-type connection must be made between the lead or leads and the housing, but the connection must also afford the possibility to disconnect the stimulator housing from the implanted leads for replacement or servicing of the stimulator.
The connective parts of the stimulator and the leads have been substantially standardized in the pacing field, and generally a relatively deep female socket is used at the stimulator housing, which has a number of contact surfaces, and the lead or leads have a male portion carrying one or more corresponding, peripherally disposed, generally circular, contact surfaces.
Conventionally, the socket portion of the connection is made of a transparent material, usually epoxy resin, which is molded onto the stimulator housing, encompassing contacts which extend outwardly from the housing. The male portion of the lead is normally locked in this socket by set screws, although many other fastening arrangements are known in the art. The positioning and alignment of the different contact surfaces, and the positioning and alignment of the metallic threads for the set screws, prior to the molding of the female portion of the connector is relatively complicated, and there is also an unavoidable delay in the manufacturing process which arises due to the time needed for the epoxy resin to cure.
Moreover, since the connector is disposed at the top of the stimulator housing, the two halves of the housing which are joined together, after the circuit, power source and other components have been mounted therein, must necessarily be non-identical, and are usually mirror-symmetric. This requires that two differently shaped housing halves be manufactured and maintained in inventory.